"Rich" wrote ...

In infinite wisdom Paul Blay answered:

"Andrew Nowicki" wrote ...

If you are making a dent in the trunk, you can estimate
how much time it will take finish the chopping.

I posit that there are people who are sometimes absent minded enough 
to put on only one sock in the morning.  In order to test this I get 
permission to put a camera at ankle height in a ticket machine in an
underground station that has a few thousand people pass through each
day.  After analysing one day's results I have found no one-sock 
wearing people.

Based on these results what is the estimated time until I find a one-sock
wearer?

[massive snip]

You've missed the point which is simply that there is no way to determine 
the time to observation of X based solely on having had no previous 
observations of X.

Actually that's not quite right - but the statistics involved don't really prove
anything.  [e.g. You could say that, based solely on having looked for 60 
years and not found anything, then the chance you'll find something in the 
next year is 1%]